Electric igniter system for fuel burners and the like



Sept. 3, 1968 M. 1.. MILLER 3,400,302

ELECTRIC IGNITER SYSTEM FOR FUEL BURNERS AND THE LIKE Fig. l

l l :27 I7 2O 2| l ocoooooo Q I I I c2 W2 l I INVENTOR MARSDEN L. MILLER BY Q2367 ATTORNEY M. L. MILLER Sept. 3, 1968 ELECTRIC IGNITER SYSTEM FOR FUEL BURNERS AND THE LIKE 2 Sheets-Sheet 2 Filed April 1, 1966 INVENT OR ATTORNEY United States Patent 3,400,302 ELECTRIC IGNITER SYSTEM FOR FUEL BURNERS AND THE LIKE Marsden L. Miller, Westfield, N .J., assignor to Ranco Incorporated, a corporation of Ohio Filed Apr. 1, 1966, Ser. No. 539,516 9 Claims. (Cl. 31796) The present invention relates to an electric spark type ignition system for fuel burners particularly suitable for use on cooking stove and the like.

The principal object of the present invention is the provision of a new and improved electrical igniter system for fuel burners, such as cook stoves, which is simple in construction, reliable in operation and which produces repetitively, strong ignition sparks with a minimum of electrical current consumption. The system is particularly suitable for igniting individual burners in a domestic fuel gas cooking stove so that standing flame-type pilot burners and their attendant heat are eliminated without impairing the efliciency of ignition of the burners.

In carrying out the invention, a transformer is provided having a primary winding which energizes the secondary winding thereof and furnishes a high potential, low current to spark gap means connected in circuit therewith and located in the gas discharge of the burner to be ignited, the primary winding being periodically energized and de-energized by a surge voltage actuated switching means in circuit therewith, which is in turn energized by a resistance-capacitor network connected across a power source, so that the expansion and collapse of the field of the primary winding induces a spark producing potential in the secondary circuit. The switching means is preferably a solid state type, such as a silicon controlled rectifier or a voltage break-down diode. The source voltage may be either AC or DC and can conveniently be the usual 120 v. AC.

Other objects and advantages of the invention will be apparent from the following description of preferred forms thereof, reference being made to the accompanying drawings wherein:

FIG. 1 is a fragmentary view of a cooking stove, shown in schematic form, including an ignition system embodying the invention;

FIG. 2 is a wiring diagram of one form of an ignition system embodying the invention; and

FIG. 3 is a wiring diagram of a second form of the invention embodied in an ignition system.

Referring to FIG. 1, an oven 0 of a conventional gas stove is shown schematically which includes two gas burners and 11 which are the broil and bake burners in the top and lower portions of the oven, respectively. Fuel is fed to the burners by suitable gas valves and may include thermostatically and timer controlled valves, which are not shown inasmuch as they are unnecessary to the understanding of the invention. The fuel at burner 10 is ignited by an igniter pilot burner 13 which comprises a tube 14 having slot-like openings 15 along the top thereof and gas fuel is fed to the tube through a conduit 16 connected with a suitable gas fuel valve mechanism of any suitable type which supplies gas to the pilot when the gas fuel for the burner 10' is to be turned on. The tube 14 is supported on a metal bracket 17 which is attached to a. suitable metal surface 18 comprising a part of the oven, and which bracket supports an electrode 20 encased in a ceramic sleeve 21. The electrode 20 is connected by a wire 22 to a terminal 23 on the ignition control panel 24 which may be installed in any convenient location, such as to the rear of a control panel of the stove, not shown. The bracket 17 includes a second electrode 25 which is spaced from electrode 20 whereby the gas between the electrodes 20, 25 may be ionized and a 3,400,302 Patented Sept. 3, 1968 spark produced in the gas issuing from the tube 14 when a high electrical potential is applied between the electrodes.

The burner 11 is adapted to be ignited by an igniter pilot burner 26 similar to that described with reference to the pilot burner 13 and the pilot burner is adapted to be ignited by spark means similar to that comprised of the electrodes 20, 25 and like parts of the pilot burner and spark means are referred to the same reference characters having a prime added thereto. The electrode 20 is connected, however, by wire 27 to a second terminal 28 on the ignition control panel 23. It will also be understood that before the fuel for burner 11 is admitted to the manifold for the burner, fuel gas is first admitted to the tube 16 for igniting the gas flowing from the tube 14 by valving well known and therefore not shown.

Referring now to control panel 24 and the ignition control circuit 30 thereon, the circuit includes power supply terminals 31, 32 to which power lines L1, L2 are connected with provide v. AC, which is the usual domestic type power service. Any other suitable power service could be employed, however.

The control circuit includes a step-up transformer T having a primary winding 33 and a secondary winding 34, the ratio of the windings being preferably in the order of one to one hundred sixty so that an exceedingly high voltage will be induced in the circuit of the secondary winding as described hereinafter. Opposite ends of the secondary winding 34 are connected with the terminals 23 and 28, so that the circuit for the winding includes the spark gaps at electrodes 20, 25 through ground and electrodes 20', 25, as shown.

One side of the primary winding 33 is connected to a conductor 35 which is connected with the terminal 31 through a circuit comprising a diode type rectifier D1 and a resistor R1 in series circuit. The side of the winding 33 is connected with the terminal 32 through a silicon controlled rectifier 36 which is connected to a conductor 37 to terminal 32.

The gate 38 of the rectifier 36 is connected to one terminal of a neon discharge tube 40, the other tube terminal is connected in an RC network comprising a series connected resistor R2 and capacitor C1 connected to the junction 41 between the diode D1 and resistance R1. Resistor R2 and capacitor C1 are arranged so that the unidirectional current through diode D1 builds up across C1 over a period, a potential sutficient to break down the neon tube 40 whereupon the capacitor discharges through the tube and triggers the controlled rectifier 36 to complete the circuit for the primary winding 33 through the controlled rectifier.

The current for energizing the primary winding 33 is obtained from a capacitor C2 which is connected in parallel with primary winding and the controlled rectifier 36. The capacitor C2 is charged through resistor R1, which is of lower value than resistor R2, so that capacitor will be charged ahead of the charging of capacitor C1 to the neon tube 40 discharging potential. When the circuit for the primary winding 33 is completed through rectifier 36, capacitor C2 discharges through the primary winding and the momentary surge of discharge current induces a high voltage surge in the secondary circuit 34 thereby creating sparks at the igniter electrodes 20, 25 and 20', 25' in the order of from 10 to 25 kv. to ignite any fuel which may be issuing from the adjacent igniter pilot burners. The rate at which resistor R2 and capacitor C1 act to trigger the rectifier 36 will be determined by their respective values which can be readily determined for the periods desired by those skilled in the art.

The power through lines L1, L2 to energize the ignition system may be controlled in any convenient manner as by switches or other control circuitry, not shown, which shorts out the terminals 31, 32 to terminate operation of the igniter. Since many variations of control of the ignition system can be employed by those well versed in the art, such details are not shown here.

An optional safety resistor R3 is connected in parallel with capacitor C2 and is of relatively high value for the purpose of draining off capacitor C2 after the circuit igniter has been de-energized.

As an example of the components and their values in a typical igniter system for 115 v. AC current supply of the type described, diode silicon D1 has a value of 400 v., 125 ma; R1 1,0009; R2 22 megohms, C2 20 mfd., 250 v. The rectifier 34 is RCA ZN 3528 and the neon tube 40 is typically Signalite A-l63, resistor R3 MS2.

Referring to the form of the ignition circuit 50 shown in FIG. 3, the circuit is mounted on a suitable frame or panel 51 and includes two power input terminals 52, 53 to which lines L3, L4 of a domestic 115 v. AC power supply are connected. One or both the lines L1 and L2 may have a switching means therein by which the circuit 50 may be energized when it is desired to ignite any of the burners. A transformer T1 is provided which is like transformer 32 and comprises a primary winding 55 and a secondary winding 56, the terminals 57, 58 of which are adapted to be connected in a circuit including spark gap electrodes like electrodes 20, 25, and adjacent pilot burners, but which for sake of conciseness are not shown. One terminal of the primary winding 55 is connected with power terminal 52 through a circuit comprising a diode D2 and a resistor R4. The other terminal of the primary winding 55 is connected to the power terminal 53 by a circuit including a voltage breakdown diode 60.

A capacitor is connected in parallel with the primary winding 55 and the diode 60, one side being connected at the junction of the resistor R4 and the winding 55.

When the circuit is energized, capacitor C3 is charged through diode D2 and resistor R4 and the circuit for the primary winding is initially blocked by the diode 60. When the capacitor C3 has charged to a potential which will break down the diode 60 and complete the circuit for the primary winding 55, capacitor C3 then discharges a surge of current through the primary winding, thus momentarily inducing a high potential in the secondary 56 which draws sparks between the electrodes of the spark gap means connected in circuit therewith.

It will be seen that the circuit 50 is exceedingly simple, is constituted of a minimum number of relatively inexpensive and reliable components which produce high voltage, low current igniter sparks with a use of a minimum amount of current. The voltages attained for the spark circuit are in the order of 10-25 kv. but the current is so small that radio interference will not occur therefrom and the energy is not generally considered hazardous.

It has been found that for use in a v. AC circuit the values of elements are as follows:

Diode D2 400 v., ma. Resistance R4 3009. Capacitor C3 2O mfd., v.

Breakdown diode- Hunt Electronics type LD4, 95 v.,

700 milliamps.

Although but two forms of the invention have been shown and described in detail, it will be understood that other forms, modifications and adaptations could be made all falling within the scope of the claims which follow.

I claim:

1. An igniter system comprising a transformer including a primary winding and a secondary winding, spark gap igniter means connected in circuit with said secondary winding, a source of electric current including two conductors connected to opposite sides of said source, one terminal of said primary winding connected to one of said conductors, circuit means connecting the other terminal of said primary transformer winding to the other of said conductors and including semiconductor switch means in series with said primary winding and responsive to a surge of current to render the circuit for said primary winding conductive, a capacitor connected in parallel with said primary winding and discharging through said primary when said switch means conducts, and means to periodically render said switch means conductive including an RC network comprising a second capacitor connected in parallel with said primary winding and to a control electrode of said switch means.

2. An igniter circuit as defined in claim 1 further characterized by said second capacitor connected between said conductors and resistor means connected between one of said conductors and said capacitor.

3. An igniter system as defined in claim 2 wherein said source is an alternating current source and further including a diode between the last mentioned one conductor and said resistor means to provide a unidirectional current for charging said second capacitor.

4. An igniter circuit as defined in claim 1 further characterized by said switch means comprising a silicon controller rectifier.

5. An igniter system comprising a transformer including a primary winding and a secondary winding, spark gap igniter means connected in circuit with said secondary winding, a source of electric current including two conductors connected to opposite sides of said source, one terminal of said primary winding connected to one of said conductors, circuit means connecting the other terminal of said primary transformer winding to the other of said conductors and including semiconductor switch means in series with said primary winding and responsive to a surge of current to render the circuit for said primary winding conductive, means to periodically render said switch means conductive including an RC network comprising a capacitor connected in parallel with said primary winding and switch means, said switch means comprising a silicon controlled rectifier, said RC network including a voltage divider circuit including a first resistance and said capacitor, said capacitor connected between said conductors and in parallel with said primary winding, a second capacitor connected between said conductors and in parallel with said primary winding, a voltage discharge tube connected between said voltage divider circuit and the base cathode terminal of said silicon controlled rectifier, and a second resistance in circuit between said source and said second capacitor.

6. An igniter circuit as defined in claim 5 further characterized by said second resistor having appreciably less resistance than the first mentioned resistance and said second capacitor having a greater capacity than said first mentioned capacitor.

7. A low frequency igniter system for fuel including conductors connectable to an alternating current power supply; a transformer having a primary winding connected across said power supply and a secondary winding connected across a spark gap; voltage responsive conductor means connected in series with said primary winding, said conductor means operable to conduct current in response to a predetermined voltage thereacross; circuitry for rendering said conductor means conductive comprising a resistance capacitance network including a resistor, and a capacitor connected across said conductor means and primary winding; and a unidirectional conductor connected between said power supply and said capacitor, said unidirectional conductor providing for charging of said capacitor by a pulsating direct current and said resistor retarding the charging rate of said capacitor so that said predetermined voltage is established across said capacitor only after a number of alterations of said power supply, said predetermined voltage rendering said switch means conductive and said capacitor discharging through said primary causing an ignition spark at said spark gap.

8. A low frequency igniter system as defined in claim 9 wherein said voltage responsive means provides a minimal resistance to current flow in the direction opposite to the discharge current from said capacitor.

9. An ignition system for a burner comprising, an electric power supply, a step up transformer including a primary winding connected across the power supply and a secondary winding inductively coupled to said primary winding, spaced elements defining a spark gap across said secondary winding, a semiconductor switch operable between a conductive and a nonconductive condition and connected in a circuit With said primary winding, said switch including a control electrode responsive to an electrical impulse to render said switch conductive, a capacitor connected in a circuit with said primary and said switch means, said capacitor being charged when said switch is in one condition and discharging through said primary winding when said switch is in said other condition and circuitry for controlling the condition of said switch to alter the charge condition of said first capacitor including a resistor and second capacitor connected to said power supply to provide a predetermined R-C time relationship to the voltage level across said second capacitor, a voltage responsive conductor connected to a plate of said second capacitor and the control electrode of said switch, said voltage responsive conductor being rendered conductive in response to the establishment of a first voltage level thereacross and rendered non conductive at a second lesser voltage level thereacross, said voltage responsive conductor rendered conductive when said second capacitor reaches a charge condition sufliciently great to produce said first voltage level across said voltage responsive conductor and said second capacitor discharging through said conductor, said capacitor and voltage responsive conductor cooperating to periodically change the conductive condition of said switch and thereby effect discharging of said first capacitor through said primary Winding to produce a spark at said gap.

References Cited UNITED STATES PATENTS 3,045,158 7/1962 McNulty et a]. 315-183 3,166,689 1/1965 Butenbuch 317-80 3,225,695 12/1965 Kapp et al. 102-702 3,311,789 3/1967 Remy 317-86 3,336,506 8/1967 Frank 317-96 BERNARD A. GILHEANY, Primary Examiner.

VOLODYMYR Y. MAYEWSKY, Assistant Examiner. 

1. AN IGNITER SYSTTEM COMPRISING A TRANSFORMER INCLUDING A PRIMARY WINDING AND A SECONDARY WINDING, SPARK GAP IGNITER MEANS CONNECTED IN CIRCUIT WITH SAID SECONDARY WINDING, A SOURCE OF ELECTRIC CURRENT INCLUDING TWO CONDUCTORS CONNECTED TO OPPOSITE SIDES OF SAID SOURCE, ONE TERMINAL OF SAID PRIMARY WINDING CONNECTED TO ONE OF SAID CONDUCTORS, CIRCUIT MEANS CONNECTING THE OTHER TERMINAL OF SAID PRIMARY TRANSFORMER WINDING TO THE OTHER OF SAID CONDUCTORS AND INCLUDING SEMICONDUCTOR SWITCH MEANS IN SERIES WITH SAID PRIMARY WINDING AND REPONSIVE TO A SURGE OF CURRENT TO RENDER THE CIRCUIT FOR SAID PRIMARY WINDING CONDUCTIVE, A CAPACITOR CONNECTED IN PARALLEL WITH SAID PRIMARY WINDING AND DISCHARGING THROUGH SAID PRIMARY WHEN SAID SWITCH MEANS CONDUCTS, AND MEANS TO PERIODICALLY RENDER SAID SWITCH MEANS CONDUCTIVE INCLUDING AN RC NETWORK COMPRISING A SECOND CAPACITOR CONNECTED IN PARALLEL WITH SAID PRIMARY WINDING AND TO A CONTROL ELECTRODE OF SAID SWITCH MEANS. 